I have had two different characters earn the title 'Bouncer' off these crazed mercs, and tonight the "Forgotten Crypt key" dropped, so I figure it must be a rare drop, considering the number I have taken out.
I have looted Greater and Minor Nebulous Dream Fragments, Leather Roll, Steel Ingot, Medicinal Herb, Dream Sapphire, Nightmare Ruby, Excellent Silk, Immaculate Silk, Flawless Animal Pelts, Blue and regular Diamonds, Elegant Defiant Square Hammer, and some uncut gems.
Some further AA grinding resulted in the following loots: Median Nebulous Dream Fragment, Terror Infused Linked Coat, Elegant Defiant Breastplate, Pristine Privit, Pristine Oleander, Cloth Bolt, Lumber Plank and Extraplanar Silk.